Well I know that total volume is 12,84cm3 so 12,84cm3=Vquartz+Vgold so Vquartz=12,84cm3 -Vgold and Vgold=12,84cm3 -Vquartz but I really don't know where to move from here because using one of those in my formula I would run into the same problem as with when I would replace mass.